Speed regulation system



Sept. 5, 1944. PQTTS 2,357,285

SPEED REGULATION SYSTEM Filed April 21, 1941 2 Sheets-Sheet l INVENTORJ A 1 TORNEY.

LOUIS M. POTTS Sept. 5, 1944. M. 'POTTS SPEED REGULATION SYSTEM Filed April 21, 1941 2 Sheets-Sheet 2 INVENTOR LOLHS M. PQTTS ATTORNEY Patented Sept. 5, 1944 UNITED STATES PATENT OFFICE SPEED REGULATION SYSTEM Louis M. Potts, Evanston, Ill., assignor to Teletype Corporation, Chicago, 111., a corporation of Delaware Application April 21, 1941, Serial No. 389,624

20 Claims.

In accordance with one embodiment of the invention particularly as applied to a driving motor for printing telegraph apparatus, a pair of resistance shunting contacts are held closed by a centrifugal governing device until the motor attains a predetermined speed whereupon the centrifugal device releases the contacts which are then controlled by a pair of.cooperating cams mounted on a shaft. One of the cams is slidably keyed on the shaft which is driven by the motor through a friction clutch which tends to drive the shaft slightly faster than the natural rate of oscillation of an escapement mechanism driven by an escapement wheel on the shaft. The other cam is rotatable about the shaft and is not slidable on it, being driven positively from the motor. The cam slidable on the shaft closes the pair of contacts each time it is actuated by the positively driven cam due to the difference in speed of rotation of the two cams. Thus since the escapement driven cam moves step by step and the motor driven cam moves at a uniform rate, the resistance shunting contacts will be repeatedly closed and opened during the operation of the motor. The relative length of time the contacts are closed or opened will determine the speed of the motor and changes will be compensated for by a slight change in phase of the cams.

A better understanding of the invention will be had by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein Fig. l is a plan view of a speed controlling apparatus, embodying the present invention, shown secured in position on a motor the speed of which is to be controlled;

Fig. 2 is a vertical sectional view taken substantially along the line 2--2 of Fig. 1 in the direction of the arrows;

Fig. 3 is an enlarged view of certain of the parts illustrated in Fig. 2;

Fig. 4 is a view in perspective of a portion of the escapement mechanism showing the balance wheel and its spring;

Fig. 5 is an exploded view in perspective of the details mounted on the main governor shaft;

Fig. 6 is a right-hand elevational view of the structure shown in Fig. 2, parts being broken away to show some of the parts of the escapement mechanism more clearly.

Figs. 7 and 8 illustrate in opposite positions to a larger scale certain parts of the balance and escapement mechanism shown in Fig. 6.

Fig. 9 is a circuit diagram of the electrical connections for the motor; and

Fig. 10 is a circuit diagram showing an alterplace of the hate circuit which may be used in circuit shown in Fig. 9.

Referring now to the drawings wherein like reference characters designate the same parts throughout the several views there is shown in Fig. l a motor III to the'casing of which there is suitably secured, for example by means of a post or posts 9, a main governor mounting plate I! having bearing plates l2 and I3 secured thereto in any suitable manner. The bearing plates 12 and I3 support a pair of shafts i4 and l 5 between them, the shaft ll being adapted to support an escapement wheel l6 which is secured to the shaft H by means of a pin ll passed through its hub l8. Formed integrally with the hub I8 is a clutch sleeve 24 (Fig. 5) which has flattened sides adapted to receive driven clutch plates 25 which have central apertures 26 corresponding in configuration to the outer configuration of the sleeve 24, so that while the plates 25 may be moved longitudinally of the sleeve 24, they are not rotat able thereabout, and if rotated will drive the sleeve and the shaft H with them.

The plates 25 are interposed between driving plates 21 which have a circular central aperture 28 formed in each of them and also which have formedthereon diametrically opposed notches 29.

The driving plates 21 are freely rotatable about the clutch sleeve 24 and have pins 30 which extend outwardly from a gear 3| nested in the diametrically opposed slots or notches 29 in each of them whereby when the gear H is rotated, the drivingclutch plate 21 will be driven with it positively and will tend to drive the plates 25 through the frictional engagement therebetween, thus to impart motion to the shaft l4. Since the sleeve 24 is formed integrally with the escapement wheel IS, the escapement wheel 16 will be driven with the sleeve 24 and shaft ll to actuate its escapement, mechanism which will be described hereinafter.

A spur gear 38 which is freely rotatable on the shaft 14 has an extending hub 35 with which the gear 3| is positively connected by means of a key 34 (Fig. 2). Therefore, when motion is imparted to the gear 3|, the gear 36 will be positively driven at the same speed as the gear 3|, and. the

:meshing with and being driven by the gear 36.

A collar or spacing member 45 is provided for suitably spacing the hub member 42 from the plate l3 so that the gears 43 and 44 will mesh with the gear 36 and a gear 46, respectively. As will be apparent by reference to Figs. 2, 3 and 5, the gear 46 is fixed by means of a lock nut 48 to an irregularly shaped cam sleeve 49. The cam sleeve 49 is freely rotatable in a bearing 58 fixed in the side plate l3 and the bearing 50 abuts the left face (Fig. 2) of the gear 46 to properly position the gear with'respect to the gear44. The cam sleeve 49 hasa circular plate formed in-- tegrally with it and extending outwardly to terminate in a threaded flange 52 on which a looking ringv 58 and a cap 54 are threaded. The

cap 54 is frusto-conical in configuration and ishollowed toreceive a pair of spheres 55. The spheres 55 are relatively heavy and will be thrown outwardly upon rotation of the cam sleeve 49 and the mechanism supported thereby, the spheres 55 being interposed between the inner surface of the cap 54 and a shouldered sleeve 56 which is normally urged. to the left (Fig. 2) by a coil spring 57 interposed between sleeve 55 and the circular plate 5| formed integrally with the sleeve 69.

The cam sleeve 59 terminates in a cam surface as shown at 89, and this cam surface cooperates with a cam surface 5i formed on the right end (Figs. 2 and 3) of a contact actuating cap 83. The cap 83 is slidable on the shaft Hi, being keyed thereto by means of a pin 79 fixed in the shaft l4 and entering into a slot- H in the cap 63. The cap 83 has fixed to it, a sleeve l2 which is secured adjustably to the cap 63 by means of a set screw l3 and which is of a diameter corresponding to the diameter of the sleeve portion of the shouldered sleeve 56. The cap 85 engages a contact lever i l and when the device comes to rest as shown in Fig. 2, the spring 5? will move the shouldered sleeve 56 to th left, thereby to engage and move the sleeve 72 to the left and since the sleeve His fixed to the contact actuating cap 83, the contact lever M will be rocked counterclockwise about a pivot '15 by the action of the spring 51 to close a contact pair 76. The contact pair 16 is normally urged to its open position by a contractile spring ll fixed to the lever '14 and to an adjacent portion of the plate H3. The right-hand member (Fig. 2) of the contact pair 16 is mounted on an L-shaped member 18 and is urged to rock in a clockwise direction by a spring '19 until it engages a threaded abutment 80 which may be adjusted to any desired position and locked in that position by an associated lock nut 8 l.

The apparatus described hereinbefore tends to drive the escapement wheel H6 at a slightly faster rate than the cam sleeve 99. The escapement wheel l8 has a single escapement cam 85 formed on the shaft 15. The balance wheel 99 is interconnected with a retainer member 9| by a hellcal spring 93which has a predetermined number shaft i l will be stopped momentarily. Anchor 88 however, is engaged by pin 89 to rotate pallets 86 and 81 to their other position with the result that shaft l4 and cam 85 are released for rotation and will be rotated by power communicated through the friction clutch. Cam in rotating engages the end of the vertical surface of the pallet which had caused stoppage of shaft i 9 and forces anchor 88 to its other position where the opposite pallet will engage a radial surface of cam 85 and again stop shaft l4. Such operation is repeated for each movement of the balance wheel 90. In assembling the balance Wheel, spring and anchor, the retainer member 9! is adjusted and locked in place by means of a lock screw 92 (Fig. 4) to hold the impulse pin 89 on the balance wheel 98 exactly on a line drawn from the center of shaft l5 to the center of pin 98. This assemblage, constituting an escapement mechanism, will tendto reduce the speed of the shaft iii in accordance with the natural rate of oscillation of the balance wheel 99 and its spring- Although numerous forms of control circuits for controlling the speed of the motor under the influence of the contact arm 3 might be provided, one which is especially effective is shown in Fig. 9 wherein the motor i0 is shown as being connectable to either an alternating current source 96 or a direct current source 97. An impedance is connected across the leads from the current sources to the motor and a variable resistance 98 is always in the motor circuit. In addition to the resistance 98, there is provided a variable resistance 99 which will either be in circuit or will be shunted by the contact l8. Connected in parallel with the resistance 99 are a series connected resistance Hi8 and a condenser it! which serve the usual purpose of spark protection and the condenser lili is made larger than necessary for spark protection so that when the motor is connectedto the alternating current source its starting torque will be increased.

When the circuit just described is switched from alternating current to direct current, the motor will operate at the same speeddue to the fact that the impedance 95 will draw a certain amount of current when the motor i9 is connected to the alternating current source 98 but will draw appreciably more current when the motor is connected to the direct current source 97. Thus, by a proper choice of impedance and adjustment, the circuit will cause the motor t run at the same speed when connected to either current source.

A better understanding of the invention may be had from the following brief description of the mode of operation of the various mechanisms therein in their control of the circuits shown in Fig. 9. When the switch which supplies either A. C. or D. C. to the motor as shown in Fig. 9

is thrown to one of its operative positions, the

I contact arm 14 will be held in its normal position where it will maintain the contact pair 18 closed due to the fact that the pressure of spring 51 which is stronger than spring 11 will force the sleeve 56 to the left (Figs. 2 and 3) thereby to move the contact member 83 to the left since the sleeve 56 will abut and move the sleeve 12, thereby to carry the member 83 to the left (Figs. 2 and 3). As the motor picks up speed the spheres 55 will tend to move outwardly due to centrifugal action and in so moving will engage between the shoulder on the sleeve 58 and the cap 54 to compress the spring 51, aided, of course, by the spring 11 to the dotted line position shown in I Fig. 3. Since the motor, through shaft 33 and gear 32, positively drives the gear 3| in the direction indicated by the arrow (Fig. 1), the thrust applied to the gear 3i will be to the right (Fig. 2), thereby tending to press the driving and driven clutch plates 21 and 25, respectively, together, and thereby to transmit rotation to the shaft l4 and escapement wheel Hi.

The gear 3| is driven at a speed somewhat faster than required to oscillate the balance wheel 98 at its natural rate of oscillation and, therefore, when the balance wheel is being oscillat d at its natural rate and the motor is running in synchronism with the oscillation of the balance wheel, it being assumed that the sleeve 56 will have moved to its extreme right-hand position under the influence of the centrifugal force exerted by the spheres 55, the sleeves 63 and 12 will be traveling at the same number of revolutions per minute as the shaft -l4 and the irregularly shaped sleeve member 49, but the shaft i l, the sleeve 63, and the sleeve l2being operable under control of the escapement mechanism will not rotate steadily but will rotate in a step-by-step movement. Therefore, there will be relative movement between the sleeve 63 and the irregularly shaped sleeve member 49 in a rotary direction, and accordingly, the cam faces 58 and at will become effective to move the sleeve '83 axially of the shaft each time this difference in motion occurs; therefore, the contact pair 16 will be repeatedly opened and closed, the contact operating lever M making two oscillations for each oscillation of the balance wheel 90 which controls the escapement wheel l5. As the motor tends to slow down, contacts l5 remain closed for longer periods of time although continuously opening and closing at a rate determined by the balance and escapement mechanism and conversely, when the motor tends to speed up, contacts 16 similarly remain closed for shorter periods of time. This is due to the fact that cam surface 88 and cam surface ESE which are constantly in engagement with each other regardless of the speed difierential between the respective elements, will have their phase relationship altered when there is a tendency for the motor to change its speed since shaft it because of its accurate speed regulation by the balance and escapement mechanism invariably makes the same number of revolutions per minute. Thus, the average length of time that the contact i6 is closed will control the flow of current in the armature circuit of the motor, thereby to control the speed of the motor by varying the resistance in the armature circuit.

From the foregoing description it will be noted that cap 55 is driven from gear 32 secured to shaft 33 of motor it) through gears 3!, 36, 43, 44, and 48 at a speed determined by the particular ratio of the'gears. Shaft l4 being driven at continuously rotating gear 3| through the friction clutch which consists of driving elements 21 and driven elements 25, will be stopped momena speed higher than the speed of cap 54 from contact for connecting variable tarily at intervals under the action of the balance and escapement mechanism. Specifically, this momentary stopping of shaft I4 is caused by the pallets and 81 alternately engaging the radial surface of cam 85 fixed to shaft I4 and operated in the manner previously described. That is, when shaft I4 is rotating at a speed different from the cap 54 or the speed of the balance and escapement mechanism which is similar in construction to that embodied in standard clock mechanisms except that driving power is supplied by a continuously driven motor, the pallets 85 and 81 of the anchor 88 will engage the leading face of cam 85 to stop shaft I4 momentarily. This condition prevails until the balance wheel 90 has rotated or returned to its other position to rotate anchor 88 clockwise through impulse pin 89 sufflcien tly to permit cam 85 and shaft l4 again to start rotation by power communicated from gear 3| through'the friction clutch which normally tends to rotate shaft H but which is precluded at intervals from doing so by action of the balance and escapement mechanism. As previously described, the release of cam 85 for rotation results in its engagement with either pallet 88 or 81, depending upon the position of the anchor 88, to impart movement to anchor 88 and in turn to the balance wheel 90. During the period shaft I4 is stopped, cap 54 continues to rotate. When shaft I4 is rotating, its speed is higher than that of cap 54 which does not have its rotation interrupted. Accordingly, during a part of the revolution cap 54 rotates ahead of shaft l4 and during the other part of the revolution shaft It rotates ahead of cap 54 so that shaft i4 and cap 54 make the same number of revolutions per minute, but they never operate at the same instantaneous speed.

If an additional load is applied to the motor there will be a tendency for a reduction in the speed of cap 54. That is, the instantaneous speed of cap 54 will vary from normal. However, due to the action of the balance and escapement mechanism, the number of revolutions per minute of haft 14 remains unchanged. Under such' circumstances there will be a greater difference in the relative speeds of shaft i 4 and cap 54 to produce a phase difference between shaft l4 and cap 5d. The phase difference, as a consequence,

will be greater so that the length of closure of contact it will be changed, although the number of closures of the contacts remains the same. With such an arrangement the speed of the motor it! is regulated through the use of the control circuit shown in Figs. 9 and 16.

An alternate form of circuit is illustrated in Fig. 10 wherein the motor the is a series commutator type of motor which may be supplied with alter rating or direct current from sources 9503 or the and. the speed of which may be controlled by a resistance the across the armature circuit of themotor. In this circuit, a condenser m5 is connected in parallel with the field @636 of the motor ltd and will have substantially no effect when the motor is connected to the D. C. source 971a. However, when the motor 68a is connected to the A. C. source 96a, the field 188 will be weakened and the armature will receive more current and the motor will tend to speed up, thus compensating for the total reduction in current.

, shaft.

Although a specific embodiment of the invention has been described hereinbefore, it will be understood that numerous modifications thereof may be made without departing from the spirit and scope of the appended claims.

What is claimed is:

1. In a speed regulating system for electric motors, means having a predetermined natural rate of oscillation, means for transmitting power [rum the motor to the means having a predetermined rate of oscillation, a shaft controlled by said means having a predetermined rate of oscillation, a sleeve driven by the motor and rotatable about said shaft, a cam formed on said shaft, a second sleeve slidable longitudinally on said shaft and rotated thereby, a second cam formed on the second sleeve and positioned for cooperation with the first cam, and a shunting contact operable by said second sleeve.

2. In a speed regulator for electric motors, a main governor shaft, a single tooth escapement device. mounted on said shaft, means having a natural rate of oscillation driven by said device, friction driving means interconnecting the motor and escapement device, a contact controlling cam element slidable on and rotatable with said shaft, a second cam element rotat- I able about said shaft by the motor and fixed against movement longitudinally thereof, a shunting contact pair in the circuit of the motor, and spring urged means tending to hold thefirst and second cams in engagement and to hold about said shaft by themotor, a shunting contact pairoperable by said contact controlling cam element, means operable under control of the joint action of said two cam elements to operate the shunting contact pair, and a governor including a sleeve concentric with the shaft for actuating the slidable camelement until theshaft attains a predetermined speed.

6. In a speed regulator for an electric motor, control means, an element positively driven by the motor, a body capable of harmonic movement deriving power from said motor, cam means controlled by said body, and means for operating said control means under the joint control of the cam means and the positively driven element.

7. ma speed regulator for an electric motor, a. frictionally driven shaft, a sleeve positively driven by said motor, an escapement device controlling the frictionally driven shaft, cooperating cam means on the shaft and sleeve, control means, and means controlled by the cooperating cam means for opening and closing said control means in timed relation to the movement of the sleeve.

8. In a speed regulator for an electric motor, means constructed to have a predetermined rate of oscillation, friction means driven at a rate proportional to the speed of the motor for tending to drive said oscillating means, cam means driven at a rate proportional to" the speed of the motor, cooperating cam means controlled by said contact pair closed, said means being reponsive to the joint action of the cams.

3. In a speed regulator for electric motors, a main governor shaft, an escapement device mounted on said shaft, means having a predetermined natural rate of oscillation driven by said device, driving means interconnecting the motor and escapement device, a. contact controlling cam element slidable on and rotatable with said shaft, a second cam element rotatable about said shaft by the motor, a shunting contact pair operable by said contact controlling cam element, means operable under control of the joint action of said two cam elements to opersaid oscillating means and control means operable in response to variations in movement of the two cam means.

9. In a speed regulator for an electric motor, a, control means, means for vibrating said control means, means independent of the vibrating means for operating said control meansand centrifugal means to render said independent means ineffective when the motor speed exceeds ate the shunting contact pair, and a centrifugal governor mounted for rotation by one of said cam elements for independently operating the slidable cam element.

4. In a speed regulator for electric motors, 9.

main governor shaft, an escapement device mounted on said shaft, means having a predetermined natural rate of oscillation driven by said motor, driving means interconnecting the,

motor and escapement device, a contact controlling cam element slidable on and rotatable with. 5 said shaft, a second cam element rotatable 1'.

about said shaft b3 the motor, a shunting contact pair operable by said contact controlling cam element, means operable under control of the joint action of said two cam elements to operate the shunting contact pair, and a centrifugal governing device for holding the slidable cam elementin its contact closing position, said governing device being mounted concentric with said 8. In a speed regulator for electric motors, a

.main gqvemor shaft, an escapement device mounted on said shaft, means having a prede= termined natural rate of oscillation drivenby said motor, driving means interconnecting the motor and escapement device, a contact controlling cam element slidable on and rotatable with said shaft, 9. second cam element rotatable a predetermined value. '3

10. In a speed regulator for an electric motor, a vibrating means including a contact having a substantially constant rate of vibration, means under the control of the vibrating means to maintain a fixed relation between the rate of vibration of the vibrating means and the speed of the motor, and means to render the means under the control of the vibrating means inefiective when the speed of the motor is below a predetermined value.

11. In a speed regulator for an electric motor, an electric circuit, a vibrating contact for controlling said circuit, means independent of the motor to determine the rate of vibration of the contact, means controlled by the .contact'to determine the speed of the motor, and means to continuously close the contact when the motor is running below a predetermined speed.

12. In a speed regulator, a' motor driven shaft, control means including a pair of contacts, a sleeve positively driven by said motor shaft, an escapement mechanism frictionally driven from said motor shaft, and means under joint control of said frictionally driven escapement mechanism and the positively driven means effective to open and close said pair of contacts.

13. In a speed regulator for an electric motor, cam means frictionally driven by said motor, cam means positively driven by said motor for "cooperation with said frictionally driven cam means, an escapement device controlling said frictionally driven cam means, and control means governed by the cooperation of said cam means for effecting a control operation in timed relation to the movement of said irictionally driven cam means.

14. In a speed regulator for an electric motor, control means, a motor driven element, a body capable of harmonic movement deriving power from said motor driven element, and an element periodically operated by said body, said elements cooperating together to regulate said control means.

15. In a speed regulator for an electric motor, continuously driven cam means, periodically driven cam means for cooperation with said first cam'means, a body capable of harmonic movement for controlling said periodically driven cam means, and a control means regulatable by the cooperation of said cam means.

16. A speed regulator 'including a driving means, cam means continuously driven by said driving means, cam means periodically operated by said driving means at a substantial constant rate of operation ior cooperation with said cam means, and an electrical-switch means for controlling said driving means regulatabl by the cooperation of said cam means.

17. In a speed regulator for an electric motor, control means, a continuously driven element, a

periodically driven element, and means to operate said perlodlcally driven element at a substantial constant rate of operation, said elements cooperating together to regulate said control means.

18. In a speed regulator ior an electric motor, control means, a continuously driven element, a periodically driven element, means to drive said periodically driven element at a substantial constant rate 01' operation, said elements cooperating together to regulate said control means.

19. In a speed regulator for an electric motor, a vibrating control means, a continuously driven element, a periodically driven element, means to drive said periodically driven element at a substantial constant rate of operation, said elements cooperating together to regulate said vibrating control means.

20. In a speed regulator for an electric motor, a continuously driven element, a periodically driven element, means to maintain said periodically driven member at a substantial constant rate of operation, and a vibrating control means regulated by the cooperation of said elements.

LOUIS M. PO'ITS. 

